Composition of cellulose ethers and esters with hydroscopic substances and the method of producing them



Patented Dec. 21,1926.

' UNITED STATES PATENT oFFicE.

CAMILLE DRE YFUS, OF BASEL, SWITZERLAND, AND GEORGE W. MILES, OF SAND- WICH, MASSACHUSETTS, ASSIGNORS TO 'THE AMERICAN CELLULOSE & CHEMICAL MFG. CO., LTD., OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

I COMPOSITION OF CELLULOSE ETHERS AND ESTEBS WITH HYDROSOOPIC SUBSTANCES.

AND THE METHOD PRODUCING THEM.

No Drawing.

Our invention relates to themanufacture of soluble cellulose-derivatives and products or articles rivauves.

A common characteristic of most, if not composed of such cellulose deall, the cellulose derivatives such as the ethers and esters, is solubility or uniform miscibility of the cellulose derivatives in or with solvent liquids, and a common characteristic of most if not all, such solvents or liquids of'suspension-is volatility. Recourse is had to the volatility of the solvent liquids for cellulose derivatives, for the production of many of the articles. of manufacture composed of these cellulosic compounds. Of these articles of manufacture, the sheets or films of cellulose ether or cellulose acetate, or the filaments of these cellulose derivatives, may .be taken as conspicuous examples.

lVhile" any such cellulose derivative is capable of being formed into films or filaments by making a solution of the .cellulosic material assume the sheet, film, or filament form under conditions favorable to the volatilization of the solvent with retention by the solute of its intended ultimate form, many such cellulose derivatives when left as a residue from solutions, are inflexible, inelastic, brittle, and in such respects me chanically inferior and unsuited to practical uses. Consequently many contrivances in the way of emollients'have been resorted to, with more or less success, in order torender cellulosic products better suited tofmiscellaneous uses.

The object of our invention is to im art to the articles of manufacture compose of cellulose derivatives,.'such as the ethers and esters of cellulose, the prime quality of flexibility, and the invention is characterized by the association with the cellulose derivative of a substance or substances which are hydroscopic, and which therefore are capable of absorbing into the body composed. of the cellulosic compoundlthus, associated with a greater flexibilit Application filed December 27, 1920. Serial No. 433,506.

flexibility of the article of manufacture composed of the cellulose derivative.

As an example and illustration, of our invention: take a cellulose acetate solution in acetone,o'f such fluidity as to be adapted to the formation of thin films, as .by flowing the solution over a glass plate. 'Mix with the cellulose acetate solution a quantity of zinc chlorid (ZnCl from two to ten per cent on the weight of the cellulose acetate dry. The zinc chlorid dissolves through the acetone solution and, when the film is formed in the usual way by volatilization of the acetone, remains uniformly dis tributed throughout the cellulosic film;

By reason of the presence of zinc chlorid, which is hydroscopic, the film is capable of absorbing Water. It will do so gradually if exposed to moist atmosphere; a simple it. Take two such test films, of equal thickness, and crease them sharply, back and forth, until the crease in each becomes a line-fracture. With ten per cent zinc chlo rid on the weight of dry acetate,in the hydroscopic film,,into which Water has been fully absorbed, the hydroscopic film has, under test, required from ten to twenty times as many foldings and creasings asthe unmodified acetate film, to produce l1ne fracture.

Another specific illustration of our invention is as' foll0ws:Prepare a solutlon of ethyl cellulose suitable for film-manufacture, using as a solvent equal parts of ethyl alcohol and acetone. To this solution add from two to ten per cent of Zinc chlor de (based on the Weight of the ethyl cellulose) and form a film from the thus prepared material. We have found that a film made from a solution containing 6% zinc chloride on the weight of the cellulose ether has much than a film of similar thickness, made 0th a cellulose ether-solution of similar consistency but havingno zinc chloride incorporated in it; It required I and residual-product, and

to produce line fracture in the film in which zinc chloride was present, as was required to produce line fracture in the film having no zinc chloride in it.

inert. Considerations of color which some hydroscopic substances may impart to the final product, will have their weight. -The fundamental requisite is,that the substance shall be miscible with the cellulosic solution shall be sufliciently hydroscopic' to absorb into the cellulose body such quantit of water-as will serve as a lubricant, emollient, or toughener,

to meet from four to seven times as many foldings,

oscopic substance by sundry practical cons1d-- mg the same 'hydroscopic substance may absorband rcthe. mechanical requirements in eachcaseQ Within such limits of proportion as are found practicable the improvement of the physical characteristics of the cellu'l-osic material will be, broadly speaking, proportionate to the amount of hydroscopic material employed.

\Ve claim:

1. A method of modifying organic cellua losic derivatives which consists in permanently incorporating m the organic cellu losic derivative asubstantially inerthydro: scoplc substance and causing the same to solidify into a mass and allowing the mass to absorb such water as the hydroscopic substance may absorb and retain.

A method of modifying cellulose acetate which consists in "permanently incorporating in the cellulose acetate a substantially inert hydroscopic substance and causto solidify into a mass and allowing the mass to absorb such Water as the tam.

3. An organic derivative of cellulose, having incorporated therein a substantially inert hydroitcopic substance and such water asthe hydroscopic substance absorbs and retains +11. The method of modifying cellulose ace- 'tat e \vhichconsists in permanently incorporating zinc chlorid 111 the body of the cellulose .acetate and solidifying the same, subsequently allowing it-to acquire such water as the zinc chlorid absorbs and retains.

5. Cellulose acetate, having zinc chlorid incorporated in its body and such water as the. zinc chlorid absorbs and retains.

(i. Cellulose acetate, having from 2 tolOfkb inc chloride incorporated therein andsuch.

water as the zinc'chloride absorbs and retains.

Signed by us at New York, N. Y., and Boston, Mass, respectively, this 14th day of December, 1920, and this 16th day of December, 1920. I DREYF US. GEORGE W. MES. 

